Nonhomologous end-joining proteins are required for V(D)J recombination, normal growth, and neurogenesis.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
H L Cheng
Publications and source records attributed to H L Cheng.
Regulation of insulin-like growth factor-binding protein-5 expression during Schwann cell differentiation.
We have reported that immortalized Schwann cells (SC) express the insulin-like growth factor I receptor and IGF-binding protein-5 (IGFBP-5). IGF-I promotes SC survival and protects IGFBP-5 in SC-conditioned medium from proteolysis. In the current study we examined the roles of IGF-I and IGFBP-5 in primary SC. IGF-I enhances primary SC differentiation and gene and protein expression of IGFBP-5 and the myelinating protein, P0. SC that stably overexpress human IGFBP-5 also have higher levels of P0 gene expression. The phosphatidylinositol-3 kinase inhibitor (LY294002), but not the mitogen-activated protein kinase kinase inhibitor (PD98059), blocks IGF-I enhancement of IGFBP-5 gene and protein expression. Collectively, these results suggest that IGF-I promotes SC differentiation, and this may occur in part by enhancing IGFBP-5 expression via phosphatidylinositol-3 kinase activation. These data support a link between enhanced IGFBP-5 expression and cellular differentiation.
Animals↗
Caveolin-1 expression in Schwann cells.
Caveolae are non-clathrin-coated invaginations of the plasma membrane, which are present in most cell types. An integral component of caveolae is the caveolin family of related proteins, which not only forms the structural framework of caveolae, but also likely subserves its functional roles, including regulation of signal transduction and cellular transport, in particular, cholesterol trafficking. Although caveolae have been identified ultrastructurally in the peripheral nervous system (PNS), caveolin expression has not previously been studied. To date, three caveolin genes have been reported. Here, we show for the first time that caveolin-1 is expressed by Schwann cells (SC) as well as several SC-derived cell lines. Caveolin-1 is enriched in the buoyant, detergent-insoluble membranes of rat sciatic nerve (SN) and SC, a hallmark of the caveolar compartment. Caveolin-1 exists as both soluble and insoluble forms in rat SN and SC, and localizes to SC cytoplasm and abaxonal myelin. SC caveolin-1 decreases after axotomy, when SC revert to a premyelinating phenotype. We speculate that caveolin-1 may regulate signal transduction and/or cholesterol transport in myelinating SC.
Animals↗
Retroperitoneal plasmacytoma associated with hyperamylasemia.
Explore the source record for details and available documents.
Aged↗
Insulin receptor substrate 2 and Shc play different roles in insulin-like growth factor I signaling.
The major substrates for the type I insulin-like growth factor (IGF-I) receptor are Shc and insulin receptor substrate (IRS) proteins. In the current study, we report that IGF-I induces a sustained tyrosine phosphorylation of Shc and its association with Grb2 in SH-SY5Y human neuroblastoma cells. The time course of Shc tyrosine phosphorylation parallels the time course of IGF-I-stimulated activation of extracellular signal-regulated kinase (ERK). Transfection of SH-SY5Y cells with a p52 Shc mutant decreases Shc tyrosine phosphorylation and Shc-Grb2 association. This results in the inhibition of IGF-I-mediated ERK tyrosine phosphorylation and neurite outgrowth. In contrast, IGF-I induces a transient tyrosine phosphorylation of IRS-2 and an association of IRS-2 with Grb2. The time course of IRS-2 tyrosine phosphorylation and IRS-2-Grb2 and IRS-2-p85 association closely resembles the time course of IGF-I-mediated membrane ruffling. Treating cells with the phosphatidylinositol 3'-kinase inhibitors wortmannin and LY294002 blocks IGF-I-induced membrane ruffling. The ERK kinase inhibitor PD98059, as well as transfection with the p52 Shc mutant, has no effect on IGF-I-mediated membrane ruffling. Immunolocalization studies show IRS-2 and Grb2, but not Shc, concentrated at the tip of the extending growth cone where membrane ruffling is most active. Collectively, these results suggest that the association of Shc with Grb2 is essential for IGF-I-mediated neurite outgrowth, whereas the IRS-2-Grb2-phosphatidylinositol 3'-kinase complex may regulate growth cone extension and membrane ruffling.
Adaptor Proteins, Signal Transducing↗
Late embryonic lethality and impaired V(D)J recombination in mice lacking DNA ligase IV.
The DNA-end-joining reactions used for repair of double-strand breaks in DNA and for V(D)J recombination, the process by which immunoglobulin and T-cell antigen-receptor genes are assembled from multiple gene segments, use common factors. These factors include components of DNA-dependent protein kinase (DNA-PK), namely DNA-PKcs and the Ku heterodimer, Ku70-Ku80, and XRCC4. The precise function of XRCC4 is unknown, but it interacts with DNA ligase IV. Ligase IV is one of the three known mammalian DNA ligases; however, the in vivo functions of these ligases have not been determined unequivocally. Here we show that inactivation of the ligase IV gene in mice leads to late embryonic lethality. Lymphopoiesis in these mice is blocked and V(D)J joining does not occur. Ligase IV-deficient embryonic fibroblasts also show marked sensitivity to ionizing radiation, growth defects and premature senescence. All of these phenotypic characteristics, except embryonic lethality, resemble those associated with Ku70 and Ku80 deficiencies, indicating that they may result from an impaired end-joining process that involves both Ku subunits and ligase IV. However, Ku-deficient mice are viable, so ligase IV must also be required for processes and/or in cell types in which Ku is dispensable.
Animals↗
Bidirectional regulation of p38 kinase and c-Jun N-terminal protein kinase by insulin-like growth factor-I.
We have previously shown that insulin-like growth factor I (IGF-I) activation of the IGF-I receptor rescues SH-SY5Y human neuroblastoma cells from high glucose-mediated programmed cell death (PCD). In the current study, we further explored the potential points in the cell death cascade where IGF-I receptor activation may afford neuroprotection. As an initial step, we examined the effects of the PCD stimulus, high glucose, on stress-activated protein kinases, specifically the two mitogen-activated protein kinases p38 kinase and c-Jun N-terminal kinase (JNK). High glucose treatment activated the tyrosine phosphorylation of both p38 kinase and JNK in a dose- and time-dependent fashion. We next examined the effects of IGF-I on JNK and p38 kinase under normoglycemic and hyperglycemic conditions. IGF-I activated p38 kinase alone and had additive effects on glucose-induced p38 kinase phosphorylation. In contrast, IGF-I inhibited glucose activation of JNK phosphorylation and JNK activity. IGF-I also inhibited the glucose-induced nuclear translocation of JNK, but did not effect glucose-induced translocation of p38 kinase. Finally, IGF-I inhibition of JNK phosphorylation was blocked by the mitogen-activated protein kinase/extracellular signal-regulated kinase inhibitor, PD98059. Collectively, these data imply cross-talk between the mitogen-activated protein kinase pathway and JNK and suggest that IGF-I activation of mitogen-activated protein kinases interferes with JNK activation and protects cells from PCD.
Androstadienes↗
RAB22 and RAB163/mouse BRCA2: proteins that specifically interact with the RAD51 protein.
The human RAD51 protein is a homologue of the bacteria RecA and yeast RAD51 proteins that are involved in homologous recombination and DNA repair. RAD51 interacts with proteins involved in recombination and also with tumor suppressor proteins p53 and breast cancer susceptibility gene 1 (BRCA1). We have used the yeast two-hybrid system to clone murine cDNA sequences that encode two RAD51-associated molecules, RAB22 and RAB163. RAB163 encodes the C-terminal portion of mouse BRCA2, the homologue of the second breast cancer susceptibility gene protein in humans, demonstrating an in vitro association between RAD51 and BRCA2. RAB22 is a novel gene product that also interacts with RAD51 in vitro. To detect RAD51 interactions in vivo, we developed a transient nuclear focus assay that was used to demonstrate a complete colocalization of RAB22 with RAD51 in large nuclear foci.
Amino Acid Sequence↗
Insulin-like growth factor-I (IGF-I) and IGF binding protein-5 in Schwann cell differentiation.
Schwann cells (SCs) are the myelin producing cells of the peripheral nervous system. During development, SCs cease proliferation and differentiate into either a myelin-forming or non-myelin forming mature phenotype. We are interested in the role of insulin-like growth factor-I (IGF-I) in SC development. We have shown previously SCs proliferate in response to IGF-I in vitro. In the current study, we investigated the role of IGF-I in SC differentiation. SC differentiation was determined by morphological criteria and expression of myelin proteins. Addition of 1 mM 8-bromo cyclic AMP (cAMP) or growth on Matrigel matrix decreased proliferation and induced differentiation of SCs. IGF-I enhanced both cAMP and Matrigel matrix-induced SC differentiation, as assessed by both morphological criteria and myelin gene expression. Cultured SCs also express IGF binding protein-5 (IGFBP-5), which can modulate the actions of IGF-I. We examined the expression of IGFBP-5 during SC differentiation. Both cAMP and Matrigel matrix treatment enhanced IGFBP-5 protein expression and cAMP increased IGFBP-5 gene expression five fold. These findings suggest IGF-I potentiates SC differentiation. The concomitant up-regulation of IGFBP-5 may play a role in targeting IGF-I to SCs and thus increase local IGF-I bioavailability.
8-Bromo Cyclic Adenosine Monophosphate↗
Growth retardation and leaky SCID phenotype of Ku70-deficient mice.
Ku70, Ku80, and DNA-PKcs are subunits of the DNA-dependent protein kinase (DNA-PK), an enzyme implicated in DNA double-stranded break repair and V(D)J recombination. Our Ku70-deficient mice were about 50% the size of control littermates, and their fibroblasts were ionizing radiation sensitive and displayed premature senescence associated with the accumulation of nondividing cells. Ku70-deficient mice lacked mature B cells or serum immunoglobulin but, unexpectedly, reproducibly developed small populations of thymic and peripheral alpha/beta T lineage cells and had a significant incidence of thymic lymphomas. In association with B and T cell developmental defects, Ku70-deficient cells were severely impaired for joining of V(D)J coding and recombination signal sequences. These unanticipated features of the Ku70-deficient phenotype with respect to lymphocyte development and V(D)J recombination may reflect differential functions of the three DNA-PK components.
Animals↗
Molecular genetic characterization of XRCC4 function.
XRCC4 is a generally expressed protein of 334 amino acids that is involved in the repair of DNA double-strand breaks and in V(D)J recombination, but its function is unknown. In this study, we have used a mutational approach and the yeast two-hybrid method to perform an initial characterization of this protein. We show that the XRCC4 protein is located in the nucleus. We also demonstrate that several potential phosphorylation sites are not required for XRCC4 function in a transient V(D)J recombination assay. In addition, we show that XRCC4 forms a homodimer in vivo with the homodimerization domain being located within amino acids 115-204. Finally, we define a core domain of XRCC4 that functions in V(D)J recombination and comprises amino acids 18-204. Potential functions of XRCC4 are discussed.
Amino Acid Sequence↗
[Validation of the Chinese version of "the Drug Attitude Inventory"].
The purpose of this study was to evaluate the validity of the Chinese version of "the Drug Attitude Inventory" and determine whether it was an effective tool for clinical evaluation. In this study, we enlisted 183 patients, 94 male and 89 female, with an average age of 34.6 years. They included outpatients, rehabilitation program patients as well as inpatients. Upon analysis of the collected data, three factors related well to the Chinese version of "the Drug Attitude Inventory", namely: subjective positive, dysphoric response, and subjective negative attitudes. In order to test the discriminant validity, we separated 53 patients into two groups, compliant and non-compliant, by appointed compliance relating to the outpatient clinic who were recent hospitalized inpatients and outpatients. These three factors correlated with each other well for most patients except for those with psychotic symptoms. These three factors demonstrated acceptable inter-item reliability (Kuder-Richardson formula 20), coefficient r and test-retest coefficient r. Construct validity was established and was capable of differentiating between compliant and non-compliant groups of patients. In short we have found the Chinese version of "the Drug Attitude Inventory" to be an effective, clinically evaluative tool. To test its predictive validity, however, further follow-up studies to determine whether these three factors discussed here can be used to predict drug compliance.
Adult↗
[The comparative study of the quality of life for outpatient care versus community rehabilitation program schizophrenic patients].
The purpose of this study was to investigate the effects of demographic variables, illness factors and symptom factors on the quality of life in schizophrenic patients. Data were collected by personal interview and self-report questionnaire druing the month from February to March in 1995. A total of 155 schizophrenic patients purposefully selected from a psychiatric teaching hospital in Kaohsiung participated in the study. The data were analyzed by descriptive and inferential statistics. The quality of life was assessed in terms the following five parameters: activity, family support, psychological well-being, physical well-being, and economic function. In addition, the work status, subjective deficits symptoms and type of treatment program were uses as predictors of the total quality of life. These parameters shared 38% of their variance in stepwise multiple regression analysis. The findings indicated that schizophrenic patients who had participated in a rehabilitation program could maintain a well quality of life than in outpatient care only.
Adult↗
Activated Ras signals differentiation and expansion of CD4+8+ thymocytes.
We describe a novel approach to assay the ability of particular gene products to signal transitions in lymphocyte differentiation in vivo. The method involves transfection of test expression constructs into RAG-1-deficient embryonic stem cells, which are subsequently assayed by the RAG-2-deficient blastocyst complementation approach. We have used this method to demonstrate that expression of activated Ras in CD4-8- (double negative, DN) prothymocytes in vivo induces their differentiation into small CD4+8+ (double positive, DP) cortical thymocytes with accompanying expansion to normal thymocyte numbers. However, activated Ras expression in DP cells does not cause proliferation or maturation to CD4+8- or CD4-8+ (single positive) thymocytes. Therefore, signaling through Ras is sufficient for promoting differentiation of DN to DP cells, but further differentiation requires the activity of additional signaling pathways.
Animals↗
Immunohistochemical localization of insulin-like growth factor binding protein-5 in the developing rat nervous system.
The insulin-like growth factors (IGF-I and IGF-II) are peptides with both growth-promoting and insulin-like metabolic effects. The IGFs interact with and are modulated by a group of six IGF-binding proteins (IGFBP-1 through IGFBP-6). Previous studies have characterized IGFBP-5 and IGF-I gene expression in the developing nervous system. In the current study, cellular and tissue-specific distribution of IGFBP-5 protein was examined in the developing rodent nervous system using immunohistochemistry. Beginning with embryonic stage E12, IGFBP-5 immunoreactivity was observed in peripheral nerves. This pattern persisted through adulthood and was detected within Schwann cells and axons after postnatal day 16 (P16). IGFBP-5 immunoreactivity first appeared in the CNS at P16. Purkinje cells of the cerebellum were immunostained at P16, P32 and in the adult. IGFBP-5 immunoreactivity was also detected in several brain stem nuclei and their corresponding tracts as well as neuroglia. Nerve tracts and glia in the postnatal spinal cord were also immunopositive, however, spinal cord neurons were not stained. The current results, coupled with the known profile of IGF-I expression during nervous system development demonstrates the colocalization of IGF-I and IGFBP-5 in PNS, cerebellum, and brain stem.
Animals↗
Characterization of insulin-like growth factor-I and its receptor and binding proteins in transected nerves and cultured Schwann cells.
The insulin-like growth factors (IGFs) are trophic factors whose growth-promoting actions are mediated via the IGF-I receptor and modulated by six IGF binding proteins (IGFBPs). In this study, we observed increased transcripts of both IGF-I and IGF-I receptor after rat sciatic nerve transection. Schwann cells (SCs) were the main source of IGF-I and IGFBP-5 immunoreactivity until 7 days after nerve transection, when invading macrophages in the distal nerve stumps were strongly IGF-I positive. In vitro, IGF-I promoted SC mitogenesis. Northern analysis revealed that SCs expressed IGF-I receptor and IGFBP-5. IGF-I treatment increased the intensity of IGFBP-5 without affecting gene expression. Des(1-3)IGF-I, an IGF-I analogue with low affinity for IGFBP, had no such effect. Incubation of recombinant human IGFBP-5 with SC conditioned media revealed IGF-I protection of IGFBP-5 from proteolysis, implying the presence of an IGFBP-5 protease in SC conditioned media. Collectively, these data support the concept that, in response to nerve injury, invading macrophages produce IGF-I and SC express the IGF-I receptor, to facilitate regeneration. This regenerative process may be augmented further by the ability of SC to secrete IGFBPs, which in turn may increase local IGF-I bioavailability.
Animals↗
Idiopathic infected hydrocele in infants: a case report and review.
Explore the source record for details and available documents.
Bacterial Infections↗
Prognostic factors of primary transitional cell carcinoma of the upper urinary tract.
OBJECTIVES: We presented and analyzed our results in order to determine the relationship between patient survival and tumor grade and/or stage. In addition, a retrospective tumor DNA ploidy study was done to evaluate its possible role in predicting future tumor recurrence in the bladder. METHODS: A total of 112 patients with upper urinary tract transitional cell carcinomas (TCCs) were recorded at our hospital. Of these, 68 patients without concurrent bladder tumors (ages ranged from 36 to 80, mean 62.4 years; male:female = 1:1.2) were treated by nephroureterectomy and bladder cuff resection. They were followed up for 14-79 months (average 38.2 months). Eight (36.4%) of the 22 patients who had stage C or D tumors had received adjuvant systemic methotrexate, vinblastine, epirubicin, cisplatin chemotherapy after surgery. DNA flow cytometry using paraffin-blocked tumor specimens was performed on the tumors of 52 patients. RESULTS: Their pathologic stages and grades were 11 at stage 0, 15 at stage A, 20 at stage B, 14 at stage C, 8 at stage D; 9 of grade I, 41 of grade II, and 18 of grade III. Postoperatively, 13 patients (19.1%) subsequently developed bladder tumors with a latent period ranging from 2 to 37 months (average 14.9 months). The difference of the tumor DNA ploidy distribution pattern among tumors of high versus low stages and/or grades is not statistically significant (p > 0.05). Overall, the 5-year survival rates for patients with low- and high-stage tumors were 100 and 66.7%, respectively; for patients with grade I-II and III tumors they were 93.6 and 28.3%, respectively. CONCLUSIONS: Patient survival was mainly related to both tumor stages (p = 0.0037) and grades (p = 0.0001), rather than to tumor DNA ploidy. For patients with grade II upper urinary tract tumors, tumor DNA ploidy seems to provide no additional predictive value on subsequent tumor recurrence in the bladder.
Adult↗